1. Technical Field
The present invention relates to a blood circuit, a blood purification control apparatus, and a priming method which are used to purify blood.
2. Description of the Related Art
Patients with decreased kidney functions resulting from disease or the like receive treatments of blood purification such as dialysis from medical experts. A blood purification circuit is equipped to a blood purification control apparatus. The blood purification circuit mainly includes: a blood circuit through which blood of a patient flows; a supply fluid circuit through which dialysate or a replacement fluid flows; and a filtrate circuit through which filtrate flows. The blood purification control apparatus controls flow of fluids flowing in the blood purification circuit so as to purify the blood of the patient safely and efficiently.
In order to prepare for purifying the blood of a patient, priming is performed. In priming, a priming fluid such as physiological saline solution is filled and circulated in the blood purification circuit, so that the inside of the circuit is cleaned and air is removed from the circuit.
The blood purification circuit is fluid pathways along which blood, dialysate, a replacement fluid, and the like flow. The blood purification circuit consists of a hemofilter, chambers, needles, tubes, and the like. The hemofilter is equipment that purifies blood by exchanging substance between blood and dialysate using principles such as diffusion and ultrafiltration. Each of the chambers is an equipment that traps air bubbles (air) in a fluid flowing in a line. The needles are equipments that are connected to the blood purification circuit in performing a treatment. The needles are inserted to a blood removal position and a blood return position of shunts or the like of the patient, in order to take blood out of a patient's body and return the blood to the patient's body. Each of the tubes is provided to connection ports of the above equipments so as to connect the equipments with each other.
The chamber is originally used to trap air bubbles included in blood in the chamber when the blood runs in an appropriate direction (hereinafter, referred to as a “forward direction”) in performing a treatment. Therefore, in order to fill the chamber with a priming fluid, it is necessary to (i) run the priming fluid in a forward direction when the chamber is set upside-down in comparison to the situation of a blood purification treatment, or (ii) run the priming fluid in an opposite direction when the chamber is set in the same manner as the situation of the blood purification treatment.
In addition, it is also difficult to fill the hemofilter with a priming fluid by running the priming fluid in a forward direction, due to the structure of the hemofilter. Therefore, like the chamber, in order to fill the hemofilter with a priming fluid, it is necessary to (i) run the priming fluid in a forward direction when the hemofilter is set upside-down in comparison to the situation of a blood purification treatment, or (ii) run the priming fluid in an opposite direction when the hemofilter is set in the same manner as the situation of the blood purification treatment.
Conventionally, a blood purification control apparatus and a priming method for the apparatus have been disclosed to circulate a priming fluid in a blood purification circuit in a direction opposite to a direction for a treatment, by connecting a pack storing the priming fluid to a blood return port and activating a pump to produce a pressure difference in a direction opposite to a direction for the treatment (see, for example, Japanese Unexamined Patent Application Publication No. 2006-175103).
Since the priming is performed to remove air bubbles and foreign substances from the blood purification circuit and the hemofilter (dialyzer), a priming fluid needs to have an amount enough to clean the circuit and the hemofilter. However, it is sometimes required to reduce the cleaning amount within a possible range for economical reasons or due to elimination of processing of replacing storage containers. Therefore, a cleaning operation using a so-called rinsing method, by which a cleaning fluid having only once passed through the circuit and the hemofilter is not discharged but re-circulated and then discharged, is also widely used (see, for example, Japanese Unexamined Patent Application Publication No. 5-19076)